1. Field of the Invention
The present invention relates to an inorganic material board which is suitable as a building board.
2. Description of the Related Art
Conventionally, as described in Japanese Patent Application Publication No. S56-37106, an inorganic material board is manufactured by dehydrating a slurry of cement, fiber material, and the like, suspended in water to form a mat, and curing and hardening this mat. The inorganic material board of this kind has excellent properties, such as bending strength, and is therefore used as a building board for inner walls and outer walls of houses.
However, in recent years, amid growing concerns about environmental problems, companies have been making efforts to suppress carbon dioxide emissions and use industrial waste products efficiently. One of these efforts includes the change of the raw materials with materials which produce less carbon dioxide in the manufacturing process.
For example, the manufacturing process for cement produces a large amount of carbon dioxide, and therefore from the viewpoint of environmental problems, cement is not a desirable raw material. However, conventional inorganic material boards have contained 50 to 75 wt % of cement, as described in Japanese Patent Application Publication No. S56-37106. Therefore, investigation has been carried out into changing from cement to blast furnace slag which produces less carbon dioxide during manufacture, or reducing the combination ratio of cement, in the manufacture of building board. Furthermore, as the raw materials the use of industrial waste products and by-products, such as coal ash or plasterboard waste, are being examined.
However, if the cement is changed to blast furnace slag, or the combination ratio of cement is reduced and the combination ratio of industrial waste products and by-products is increased, then the properties such as the bending strength of the manufactured inorganic material board are reduced and there is a risk that the board cannot be used as a building board.